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SubjectRe: [PATCH 3/3] mm: oom: show unreclaimable slab info when kernel panic
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On 2017/09/15 2:14, Yang Shi wrote:
> @@ -1274,6 +1276,29 @@ static int slab_show(struct seq_file *m, void *p)
> return 0;
> }
>
> +void show_unreclaimable_slab()
> +{
> + struct kmem_cache *s = NULL;
> + struct slabinfo sinfo;
> +
> + memset(&sinfo, 0, sizeof(sinfo));
> +
> + printk("Unreclaimable slabs:\n");
> + mutex_lock(&slab_mutex);

Please avoid sleeping locks which potentially depend on memory allocation.
There are

mutex_lock(&slab_mutex);
kmalloc(GFP_KERNEL);
mutex_unlock(&slab_mutex);

users which will fail to call panic() if they hit this path.

> + list_for_each_entry(s, &slab_caches, list) {
> + if (!is_root_cache(s))
> + continue;
> +
> + get_slabinfo(s, &sinfo);
> +
> + if (!is_reclaimable(s) && sinfo.num_objs > 0)
> + printk("%-17s %luKB\n", cache_name(s), K(sinfo.num_objs * s->size));
> + }
> + mutex_unlock(&slab_mutex);
> +}
> +EXPORT_SYMBOL(show_unreclaimable_slab);
> +#undef K
> +
> #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
> void *memcg_slab_start(struct seq_file *m, loff_t *pos)
> {
>

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